This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Europe is no stranger to powerful windstorms, but some storms capable of causing serious damage have an unusual origin. Tropical cyclones can occasionally travel north from lower latitudes and reach Europe, where they can bring damaging winds and heavy rain even after losing some of their tropical characteristics.
These storms are rare enough that their risks have been difficult to assess from historical records alone. Kelvin Ng of the University of Birmingham, UK, and colleagues have used thousands of simulated hurricane seasons to explore storms that have never actually been observed, finding that the UK and Ireland are among the parts of Europe most likely to be affected. The results, published in Geophysical Research Letters, suggest that storms comparable in severity to Hurricane Lili—which caused more than $300 million in damage in western Europe in 1996—could occur roughly once every 21 to 33 years.
Tropical cyclones are usually associated with warmer parts of the world, where they develop over tropical oceans. As they move toward higher latitudes, however, some can curve northward and eventually reach Europe. They may also undergo a transformation called extratropical transition, during which their structure and energy sources change as they interact with the weather systems of the midlatitudes.
By the time these storms reach Europe, they may no longer resemble the hurricanes that formed over the Atlantic, but they can still produce powerful winds and intense rainfall. Hurricane Ophelia, for example, affected Ireland in 2017 and caused multiple deaths, fallen trees and building damage, and left around 300,000 households without electricity. The problem is that these events are so uncommon that there simply aren't enough examples in the historical record to properly estimate how often the most damaging storms might occur.
Since 1990, only two named tropical-origin cyclones—Hurricane Lili in 1996 and Hurricane Leslie in 2018—have been recorded as causing major disasters in western Europe, according to the researchers. To get around this limited historical record, the researchers used an approach known as UNSEEN, short for UNprecedented Simulation of Extremes using Ensembles. The team used two sets of computer simulations covering the 20th century, which collectively gave the researchers thousands of possible storm tracks to analyze.
The difference was substantial. The historical atmospheric data set used for comparison contained just 55 tropical-origin cyclones that reached the researchers' European study area. The two simulated data sets contained roughly 45 and 69 times as many events, providing a much larger sample for investigating rare storms.
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